The present invention relates to apparatus for introducing groups of rod-shaped smokers' products or the like into containers, especially for introducing rows or layers of plain or filter-tipped cigarettes, cigarillos or cigars into containers of the type known as chargers or trays. More particularly, the invention relates to improvements in apparatus for introducing groups of rod-shaped articles (hereinafter called cigarettes for short) into containers (hereinafter called trays for short) in such a way that the cigarettes move axially and accumulate into stacks which can be fed into the magazines of packing machines or the like.
In many tobacco processing plants, the output of each cigarette making machine is introduced into trays and the thus filled trays are thereupon transported to packing machines, to storage or to other processing stations. As a rule, a tray filling apparatus comprises one or more endless belt or chain conveyors which transport a row of cigarettes sideways from the maker (e.g., from a machine for the production of plain or filter-tipped cigarettes) to a tray filling station, a suction head or an analogous group forming device which accepts or removes cigarettes from the endless conveyors and assembles the cigarettes into groups each of which contains a predetermined number of cigarettes in a predetermined array (e.g., an elongated row or layer of 50-100 cigarettes, depending on the diameters of cigarettes and/or the size of the tray), a pusher or analogous transfer means for moving successive groups from the group forming device into an adjacent empty or partially filled tray (such tray is preferably carried by a chain conveyor or an analogous transporting device which can move the tray stepwise along the tray filling station), and a drive for the transfer means.
The drive for the transfer means of all or nearly all presently known tray filling apparatus comprises a fluid-operated assembly, preferably a pneumatic cylinder and piston unit whose cylinder or piston reciprocates the transfer means between retracted and extended positions whereby the transfer means pushes a group of cigarettes from the group forming device into the adjacent empty or partially filled tray during movement from the retracted position. Pneumatic cylinder and piston units are simple, rugged and reliable, and the movements of their parts can be regulated with a high degree of reproducibility. However, the output of tray filling apparatus wherein the transfer means receives motion from a fluid-operated cylinder and piston unit cannot be increased at will. It has been found that the maximum output is in the range of approximately 70 cycles per minute. Such limitations are attributable to several factors. Thus, the speed of translatory movement of a pneumatically operated piston or cylinder (depending upon whether the transfer means is coupled to the piston or to the cylinder) cannot exceed a predetermined value due to inertia of valves and/or other elements which regulate the admission and evacuation of fluid from the cylinder chamber or chambers. Furthermore, once the speed of the cylinder or piston has risen to a given value, the noise level and/or stray movements (especially vibration) of parts which are associated with the fluid-operated unit exceed the permissible norms. For example, if the cylinder is of the double-acting type, alternating admission and evacuation of pressurized fluid from the two cylinder chambers is followed by impingement of the movable part (normally piston) against a suitably positioned stop which limits the extent of forward or rearward movement of the piston. Such impingement causes the aforementioned vibration and noise. Moreover, the output of tray filling apparatus utilizing one or more pneumatic cylinder and piston units can be increased only by reducing the duration of return stroke of the piston since the maximum speed or forward strokes is limited by the delicate nature of articles which are being transferred into trays. Thus, if the transfer means (e.g., an elongated pusher plate) is permitted to strike against the trailing ends of a row of cigarettes at a very high speed, the trailing ends are likely to be deformed or damaged. Limits to acceleration of the return stroke of a reciprocable piston are imposed by the fact that excessive speed entails unacceptable increase in noise level and vibration of the moving parts.
Consequently, if the output of tray filling apparatus is to be increased above 70 cycles per minute, the fluid-operated drive must be replaced with another drive.